1. Field of the Invention
The present invention relates to an information recording method and an information recording apparatus having semiconductor memory, magnetic memory, and optical memory.
2. Description of the Related Art
In the past, semiconductor memory, magnetic memory such as hard disks, and optical memory such as optical discs have been used as recording media for recording large amounts of information. The above memory types are not normally treated as a single storage unit, but instead are treated as respectively independent memory types.
In contrast, in recent years hybrid memory has been proposed, being a storage apparatus wherein a hard disk drive is equipped with flash or other semiconductor memory that acts as cache memory. By causing the semiconductor memory and the hard disk to operate jointly in such hybrid memory, it is possible to increase transfer rates beyond those of storage systems made up of hard disks alone. In hybrid memory, data with high access frequency is recorded to the semiconductor memory, while all other data is recorded to the hard disk.
In addition, a database system for recording medical imaging information has been proposed, wherein information with high usage frequency is stored in a relatively high-speed recording apparatus, while information with comparatively low usage frequency is recorded to a relatively low-speed recording apparatus. In this system, devices such as a CCD (charge-coupled device) or magnetic disk are used as the high-speed recording apparatus, while an optical disc apparatus is used as the low-speed recording apparatus. (See Japanese Unexamined Patent Application Publication No. H11-145916.)